This application claims the priority benefit of Taiwan application serial no. 88122888, filed Dec. 24, 1999.
1. Field of the Invention
The invention relates to a back-lighted autostereoscopic display, and more particular, to a back-lighted autostereoscopic display with a very light weight and very thin dimension having a micro lens array.
2. Description of the Related Art
In a conventional three-dimensional display, an alternative array of thin stripes with different polarization states can be aligned to a liquid crystal display panel with interlaced parallax images to display stereoscopic images. For example, a micro-polarizer is shown in FIG. 1A to FIG. 1C, which is disclosed in U.S. Pat. No. 5,327,285 and U.S. Pat. No. 5,844,717. For an observer to see a three-dimensional image, the left eye and the right eye are to receive the lights with different polarization. Therefore, two polarization plates 102 and 104 with polarization types perpendicular to each other are laminated as shown in FIG. 1A to FIG. 1B. The laminated plate 106 thus comprises the first polarization type areas and the second polarization type areas, and the polarization directions 112 are alternating with each other as shown.
As shown in FIG. 1C, with the laminated polarization plate 106 coupled to the liquid crystal display panel 108, an observer can observe a three dimensional image only by wearing a pair of polarization glasses 110. This is not convenient and natural to the observer, and sometimes induces headache or giddiness. In addition, the stereoscopic effect will get worse while the size of the display area becomes larger.
For the convenience of the viewer(s), the system that enables the observers to see three-dimensional images without wearing the polarization glasses has been developed. FIG. 2 shows a stereoscopic display of projection type that enables the observers to see a three-dimensional image without wearing a pair of polarization glasses. As shown in FIG. 2, the projection type stereoscopic display consists of a light source 202, a polarization switching apparatus 204, a Fresnel lens 206 and a micro-polarized liquid crystal display 208. Lights from the light source 202 are polarized into a first type polarization and a second type of polarization by the polarization switching apparatus 204 in front of the light source 202. The micro-polarized liquid crystal display 208 is located in front of the light source 202, and the polarization apparatus 204 is between the micro-polarized liquid crystal display 208 and the light source 202. The Fresnel lens 206 is located between the polarization apparatus 204 and the micro-polarized liquid crystal display 208 (a combination of liquid crystal display 108 showing interlaced parallax images and laminated polarization plate 106 in FIG. 1C). Through the Fresnel lens 206, the observer 210 is able to see the stereoscopic images with naked eyes from the projection type stereoscopic display, However, this light projection structure is still in a large dimension and with a heavy weight and is hard to meet the commercial requirements.
A back-lighted autostereoscopic display is provided by the invention. A uniform light is emitted from a plane light source. A polarization plate is disposed in front of the plane light source to polarize the uniform light into a polarized light. An array of micro-moving window elements is disposed in front of the polarization plate to selectively change the polarity of the polarized light into another type of polarization. An array of micro-lens is located in front of the array of micro-moving window elements, thereby both the polarized light changed and unchanged pass through the array of micro-moving window elements to travel further. An imaging apparatus is located in front of the array of micro-lens, so that the lights are converged into the eyes of an observer. A liquid crystal display panel is located in front of the imaging apparatus to project the stereo-image to the observer.
The autostereoscopic display comprises further a tracking system to monitor the head position of the observer. Therefore, the lights with different polarization through the micro-moving windows and the areas outside the micro-moving windows can be thus projected into different eye of the observer respectively to obtain the stereo effect.
Thus constructed, the invention provides an apparatus as a back light source system for a liquid crystal display. The apparatus comprises the plane light source, the array of micro-moving window elements and the array micro-lens. The utilization of arrays of micro-moving window elements and the micro-lens save a great deal of space of the liquid crystal display. Therefore, the liquid crystal display can be formed very light in weight with a thin dimension. Furthermore, since all the light emitted from the plane light source, being polarized for once or several times, is to be projected to the observer. Therefore, the light intensity is higher than the conventional display system. And the area for image display can be enlarged to achieve the flat display of large display area.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.